Novel deformation processes and microstructures involving ballistic penetrator formation and hypervelocity impact and penetration phenomena

Light metallography and transmission electron microscopy techniques affording unique observations of microstructural issues in connection with a related set of novel, high-strainrate deformation processes provide some fundamental insight into the following areas: shock-wave-induced twinning, explosive welding, shaped charge development, explosively-formed penetrator phenomena, hypervelocity impact cratering in metal targets, and long, dense rod penetration/perforation of thick metal targets. Although shock wave phenomena are precursors in all these processes, deformation twins are rarely observed in the residual, process microstructures. In the case of hypervelocity impact craters, no deformation twins are observed in the crater-related target microstructures. Microbands that appear to be related to twins are observed. Melt-related phenomena are observed only in the explosive weld-wave interfaces. Jetting phenomena related to shaped charges and crater rim formation are dominated by dynamic recrystallization, which provides a mechanism for extreme plastic flow in the solid state. Differences observed between rod penetration of rolled homogeneous armor and Ti-alloy thick targets manifest themselves in distinct microstructural differences that also do not include melt phenomena.